import java.util.Arrays;

public class findOnce {
    public static int onceFind(int[] array){
        Arrays.sort(array);

        for(int i = 0;i < array.length;i += 2){
            if (array[i] != array[i + 1]) {
                return array[i];
            }
        }
        return -1;
    }
    public static void main(String[] args) {
        int[] array = new int[]{2,23,53,23,53};
        if(onceFind(array) == -1){
            System.out.println("找不到这样的数，请重新输入!");
        }else {
            System.out.println(onceFind(array));
        }
    }
}
